Command line to find prime factors up to about 20-digit
echo 126508695437909512224248055783991202837568466458231484402685101012833695221782072616255958132024366027936065250291436006570769414758361888624115246658327546032639 | ecm -n -c 74 11e3
Command line to find prime factors up to about 25-digit
echo 126508695437909512224248055783991202837568466458231484402685101012833695221782072616255958132024366027936065250291436006570769414758361888624115246658327546032639 | ecm -n -c 214 5e4
Command line to find prime factors up to about 30-digit
echo 126508695437909512224248055783991202837568466458231484402685101012833695221782072616255958132024366027936065250291436006570769414758361888624115246658327546032639 | ecm -n -c 430 25e4
Command line to find prime factors up to about 35-digit
echo 126508695437909512224248055783991202837568466458231484402685101012833695221782072616255958132024366027936065250291436006570769414758361888624115246658327546032639 | ecm -n -c 904 1e6
Command line to find prime factors up to about 40-digit
echo 126508695437909512224248055783991202837568466458231484402685101012833695221782072616255958132024366027936065250291436006570769414758361888624115246658327546032639 | ecm -n -c 2350 3e6